Once the dust settles, the Tropical Atlantic will need to be watched closely. The African dust storm we were tracking a week ago sent a large area of dry air and dust into the central Atlantic in late July, cooling the waters and largely suppressing thunderstorms activity in the region were tropical cyclones generally form. The dissipation of this dry air, combined with a wave of rising air moving around the globe and a subtle shift in the upper-level pattern, will make conditions more favorable for tropical development by the middle of August. Our next named storm of the 2013 Atlantic Hurricane Season would be Erin, and there is a decent chance it could form on or around the period of August 15-20.
- No current threat and no development expected through the 14th
- Dry air & dust is dissipating; conditions more favorable by mid-month
- Low chance for development in eastern Atlantic August 15-20
CARIBBEAN AND GULF OF MEXICO
Unsettled weather is expected in the Gulf of Mexico this weekend, largely due to an upper-level trough of low pressure moving west from the Florida straights. Conditions are not favorable for tropical cyclone development in this environment, but large areas of thunderstorms and heavy rain may affect the coastlines of Louisiana and Texas through Monday. Elsewhere, the Caribbean is largely quiet and expected to stay that way through the 15th. There is a low chance a tropical wave may develop in the eastern Caribbean around August 16-20, especially if the wave is not severely impacted by other tropical activity nearby. Even though this wave might struggle across the Atlantic, it would then encounter an environment more favorable in the Caribbean. Model data suggests there would be adequate moisture and marginally favorable upper-level conditions for possible development toward the end of this forecast period.
Water Vapor imagery Thursday continued to show a large area of dry air and dust across much of the central Atlantic, although not nearly as expansive as it was just a week ago. A wave of energy or upward motion, commonly known as the Madden Julian Oscillation (MJO), is rotating around the globe and expected to be over the Tropical Atlantic within the next two weeks. Forecast data also suggests a couple of strong tropical waves will be emerging off the west coast of Africa next week, helping to moisten the atmosphere in the eastern Atlantic. Some of the more reliable forecast models are even hinting at the idea that a tropical cyclone may form in this region late next week. It is obviously too early to talk specifics, but we are noting this region as one to watch August 13-16, with a low chance for development thereafter.
September is traditionally the peak of hurricane season in the Atlantic, but August can be a very active month as well. An average of 2.4 tropical storms and 1.3 hurricanes have formed during the month of August since 1859. The probability of a storm hitting the United States during the month of August is around 50 percent (per NOAA, http://www.aoml.noaa.gov/hrd/tcfaq/E17.html).